The Scottish National Party conference used to flit around Scotland: Dunoon, Oban, Dundee, even Rothesay have hosted it. Nowadays Perth concert hall, a glass-fronted building near what remains of the old city walls, is one of the few places large enough to hold everyone. ‘It’s got bigger,’ two white-haired women from Moray answered in unison when I asked what has changed since their first SNP conference more than three decades ago. ‘But it’s still lots of fun, especially in the evening.’

A marquee was attached to the concert hall’s main entrance. Just inside the door, a smiling woman in a tartan skirt processed delegates’ passes. Behind her, rows of stalls were squashed together: Young Scots for Independence, Falkirk Against Unconventional Gas, Network Rail, Scottish Land and Estates. ‘You used to know everybody here. Now you don’t, there’s that many. But us old stagers are still here,’ said Ian Hamilton, the business manager of the Scots Independent (‘the oldest political paper in Europe’). ‘We have become a bit more professional now, though.’ He nodded at a chip-and-pin card reader behind a pile of paperbacks on his bookstall.

A stand inside the lobby sold ‘yes’ Christmas cards and babies’ bibs with ‘future first minister’ on them. On Saturday, the current first minister told the faithful that next September’s referendum offers a ‘fundamental democratic choice for Scotland – the people’s right to choose a government of our own’. Alex Salmond described an independent Scotland free of the bedroom tax, with a higher minimum wage and a renationalised Royal Mail. The day before, the deputy first minister, in an apparent change in campaign strategy, warned of the dangers of saying ‘no’ next year: ‘If we don’t vote yes,’ Nicola Sturgeon said, ‘Westminster will turn the screw.’

Until Salmond’s rousing speech, there was a rather muted feel to the weekend’s gathering. In 2011, the SNP had a Holyrood majority to celebrate; last year, Nato membership dominated. This year was all about the referendum. Nationalist politicians talk about positive noises on the doorstep, but the opinion polls give little succour: the only good news for the SNP is some movement between ‘nos’ and ‘don’t knows’ and that the Scottish government’s approval rating is going up. At one fringe meeting, a delegate on the floor said that for the first time he felt ‘a wee bit of uncertainty’ about a ‘yes’ vote. His colleagues in the aisles growled in contempt.

Robin McAlpine, the director of the Jimmy Reid Foundation, has spearheaded a Nordic-inspired manifesto, the Common Weal, for an independent, social-democratic Scotland (‘to build more we must share more’) that has attracted support from sections of the SNP and across the broad left in Scotland. ‘We need a model of social and economic development in Scotland that is based on mutuality, not conflict,’ McAlpine told me on Friday. ‘We are a disoriented society in the most literal sense – we never look east and we never look north. We have a frame of reference that stretches only from Washington to London. We have a model that is very explicitly designed by London. Conflict is right across the piece.’ On Saturday morning SNP delegates overwhelmingly passed a motion that an independent Scotland ‘may wish to adopt’ Common Weal proposals.

An hour or so before Salmond’s speech, around a hundred protesters with anti-wind-farm placards stood in the rain outside the concert hall. A man in a Barbour jacket shouted ‘scandal, scandal’ over and over at the top of his voice. Another carried a homemade sign, covered in clear plastic: ‘Alex Salmond Scotland’s Mugabe’. A soggy-looking teenager waved a union jack. A woman with a clipped English accent asked a pair of children standing on the footpath: ‘Did you get on the TV?’